The present invention relates to an electronic projectile time detonator according to the preamble of patent claim 1. Such a detonator can be found, for example in DE 42 40 263 C1. With respect to further prior art, reference is made to U.S. Pat. No. 4,454,815, DE 39 26 585 C1, DE 38 21 912 A1 and DE 692 11 638 T2.
Currently modem electronic detonators preferably employ for the energy supply batteries, which are only mechanically-chemically activated through the great accelerations which occur when firing a projectile. This has the advantage that detonators equipped thus do not require maintenance with respect to replacement, for example of an otherwise employed battery primary cell, since these batteries are entirely passive during their storage and therefore permit long storage times. The projectile detonators equipped therewith are therefore more favorable with respect to the detonator structure, the operating life costs and the logistics than comparable detonators equipped with, for example, primary cells.
In general in the case of time detonators equipped thus the operating sequence of the previously programmed detonator running time is started through the activation of the battery, i.e. by running up the battery voltage during the mechanical-chemical activation through the launching accelerations. This type of start of the running time first also has the advantage that a separate sensor for the detection of the firing in the detonator becomes superfluous which leads to further simplification of the detonator structure.
Such time detonators, which for reasons of overflight safety in general have no impact function, are employed for initiating the breakup of a cargo-projectile, which ejects secondary munitions. Since, especially in the case of employment by the artillery, one""s own troops are also overshot, the requirements with respect to safety against too early a projectile breakup (overflight safety) are in general very high. Known numbers for the maximum permitted probability of too early a breakup are between 10xe2x88x925 and 10xe2x88x926.
In order to be able to attain such values, in the detonator electronics several measures are conventionally taken. These constructional measures extend from the application of redundant acceleration-proof oscillators, which are intended to prevent too quickened an operating sequence of the detonator running time of an individual erroneously operating oscillator, up to detonator circuits which are charged with ignition energy only very late, shortly before the point in time of the breakup.
The possibly erroneous (too early) point in time of the breakup of a projectile, however, is not only a function of the potential effects during the flight, but can also emanate from an erroneous firing command, erroneous programming of the detonator running time and erroneous start of the detonator running time in the detonator.
The two cases listed first cannot be corrected by measures in the detonator and will not be further considered here. The case listed last of the erroneous (too early) start of the detonator running time is the point of departure for the proposed improvement with respect to overflight safety.
The activatable batteries employed must constructionally be laid out such that they reliably activate within the entire temperature range even with extremely small propellant charge during the firing. On the other hand, they must withstand mechanical loading through environmental tests (for example 1.5 m drop onto steel plate) and the acceleration during the loading process without activating. Therewith by necessity the constructionally required safety margins between activation and nonactivation grow small. In addition, individual faults in the battery, which emanate from defective battery fabrication or material faults, can reduce these reserves further.
According to the above statements it can also not be excluded that such batteries already activate before the shot. If the time detonator had not been programmed before the battery activation, such an occurrence is in general only a problem of the total reliability of the detonator, for this detonator would remain without function (inactive) when later employed.
If, in contrast, it was previously programmed, with the electronics layout conventionally used up to now the detonator starts with the finishing out of the mission program, i.e. starting the running time, charging of the ignition circuits and detonation.
Before the launch, in the barrel and within a defined distance in front of the barrel (forward-of-barrel safety) the detonation of the projectile is in general prevented by a mechanical (or electronic) safety device. This safety device is laid out such that unintentional (mechanical-pyrotechnical) safety releasing processes can only occur with very low probability (10xe2x88x927 and lower).
After the regular safety releasing process of the safety device, the ignition means are in ignition position and contacted. If detonation occurs now, it leads to a breakup of the projectile. With the correct start of the running time through the launch, the breakup occurs in the intended target area.
However, if the running time was unintentionally started earlier, the breakup occurs correspondingly earlier i.e. on the ballistic path since the same programmed time span is being finished out. This unintended breakup point can thus practically be shifted backward on the complete flight trajectory up to the forward-of-barrel safety area. In particular in the case of the employment of cargo munitions conventionally used for time detonators this leads to considerable endangerment of one""s own overshot troop formations.
Especially with faulty batteries, the unintended earlier start of the running time function can already occur through the acceleration processes during the loading (ramming home) of the projectile. It can be assumed that the activation of the battery during the loading process cannot be excluded with a probability of 10xe2x88x925 to 10xe2x88x926.
When employing such detonators on previously conventional guns, which, especially in proving operation, achieve only minor shot sequences, the described safety problems have been reduced through on-path breakup, possibly through the relatively long times between ramming home of the projectile (possibility of erroneous battery activation) and firing through the inhibiting effect of the safety device. If the time between the ramming home of the projectile and the firing of the projectile is longer than the programmed flight time, the electric ignition means thus ignites already in the barrel and a further igniting through is in this case prevented through the safety setting of the safety device.
However, guns used widely today are loaded and fired automatically. The time processes are here shorter, i.e. the times between automatic ramming home of the projectile and the firing are shorter or comparable to the set detonator running times. For that reason, on such guns for electronic time detonators (with activatable battery) within prior art, the probability of on-path breaking up is increased.
Building on this prior art, the task of the present invention is therefore specifying an electronic projectile time detonator, which strongly reduces the probability of on-path breaking up.